You've just turned back on your computer and suddenly you can't get into the desktop. It gets stuck in the Windows log-on screen. And what's pretty surprising about it, the activation screen comes up and would ask you to activate again your Windows XP.

What you would normally do is to activate the product hoping you could log-on back to the desktop. Unfortunately in most cases, the activation will not work. And in some other cases, when you activate the product, it would tell you that it is already activated but does the same anoying thing after a restart.

Here's the fix that I've tested in quite a few Windows XP system. This works on either Windows XP Home or Professional. Just follow the steps in order: